As a result of recent heightened consciousness of environmental consequences in the industrial circles, technical development for mounting electronic components that have used materials not containing any lead has been progressing in the electronics field, for example. Mounting using lead-free solder or an electroconductive adhesive, for example, is under consideration as a lead-free mounting technology. More specifically, advantages such that the electroconductive adhesive is stress-resistant and use of a low heating temperature in the mounting process is possible are expected and draw attention.
A typical electroconductive adhesive has metallic particles dispersed as a conductive filler in resin components. Mounting an electronic component is carried out by supplying an electroconductive adhesive on to lands provided on a substrate, placing the electronic component thereupon, and then heat hardening the resin. Through this process, conduction is acquired through contact among the metallic particles within the resin due to constriction of the resin or contact between the metallic particles and component electrodes or substrate electrodes, and junctions thereof are bonded together by the resin. In this process, the hardening temperature of the resin used in the electroconductive adhesive is generally approximately 150° C. (degrees Centigrade), which is low in comparison to solder requiring a melting temperature of approximately 230° C. to 240° C. As a result, inexpensive other members with low heat resistance may be used as materials for constituting the mounted component and electronic circuit products, and may reduce product cost on the whole.
In place of the conventional solder, a technology for mounting an electronic component using an electroconductive adhesive is illustrated in Patent Document 1 (JP 2002-343668 A), for example. Patent Document 1 discloses a technology for forming a metal alloy layer including Cr, Co, or the like in terminal electrodes as an approach to the problem that peeling occurs at the interface of the electroconductive adhesive and tin plate electrodes when connecting an electronic component including the tin plate electrodes using the electroconductive adhesive.